Fix NPE in Settings -> Language & input -> Default -> Setup input
methods

If the InputMethodAndLanguageSettings fragment is launched in IME-only
mode, it removes most preferences, so we need to null-check them before
use.

Change-Id: I297cc9c6885f62ed6ff65937ef5da401ab7cd271
JIRA:CYAN-896

Conflicts:
	src/com/android/settings/inputmethod/InputMethodAndLanguageSettings.java